Proceedings of The Physiological Society

Physiology 2016 (Dublin, Ireland) (2016) Proc Physiol Soc 37, PCA117

Poster Communications

Thyroid hormones transporters and deiodinases mRNA expression are altered in placenta from gestational diabetes mellitus

C. Veas1,2, A. Armella1,2, A. Covarrubias1,2, M. Gonzalez3,2, E. Guzman-Gutierrez1,2

1. Faculty of Health Sciences, Universidad San Sebastian, Concepcion, Chile. 2. Group of Research and Innovation in Vascular Health (GRIVAS-Health), Concepción, Chile. 3. Department of Physiology, Faculty of Biological Sciences, Universidad de Concepción, Concepción, Chile.

Gestational diabetes mellitus (GDM) characterizes by an abnormal maternal D-glucose metabolism is associates with reduced maternal circulating free tyroxine (fT4)[1]. The human placenta regulates thyroid hormone concentration in fetal circulation by modulating thyroid hormone transporters (THTs) and thyroid hormones metabolism mediated by deiodinases (Dio) [2]. Interestingly, THTs and Dio expression in the human placenta from GDM have not been studied, yet [3]. Methods: Human placentas were collected after uncomplicated pregnancy with full-term delivery from 20 normal and 20 GDM pregnancies. mRNA from placental cotyledon was extracted with Trizol reagent and used for real time PCR for measuring THTs and Dio using the 2-ΔΔCt method. Results: Compared to normal pregnancy, GDM exhibited reduced plasma fT4 (1.36 ± 0.12 pg/mL; 0.91 ± 0.11 pg/mL, respectively, P<0.05, t-student) only during the first trimester of pregnancy. At first trimester, a negative correlation (Spearman r = -0.9021, P<0.05) between glycaemia 2 hours after glucose (75 g) load and fT4 was found. The mRNA level of monocarboxylates transporters 10 (MCT10) decreases by ~60% in a cotyledon from GDM compared to normal pregnancies. In contrast, mRNA level for L-amino acid transporters 2 (LAT2), organic anion transporter polypeptides system 1A2 and 4A1 (OATPA2 and OATP4A1) increase (4.7, 3.5, and 2.6 fold, respectively) compared to cotyledon from normal pregnancies. Furthermore, MCT8 and LAT1 mRNA levels were unaltered in GDM. Isotype 3 of Dio (Dio3) was also increased (2.3 fold), but Dio1 or Dio2 were unaltered in GDM compared to normal pregnancies. Conclusion: Reduced maternal fT4 in the first trimeter of pregnancy in GDM might be associated with placental alteration in the transport and metabolism of thyroid hormones.

Where applicable, experiments conform with Society ethical requirements